The birth of subliminal advertising reads almost like a script from a television show. In this real-life story, the spotlight falls on James M. Vicary, an independent marketing researcher.

On September 12, 1957, Vicary called a press conference to announce the results of an unusual experiment. Over the course of six weeks during the preceding summer, he had arranged to have slogans—specifically, “Eat popcorn” and “Drink Coca-Cola”—flashed for three milliseconds, every five seconds, onto a movie screen in Fort Lee, N.J., while patrons watched Picnic. Vicary argued that these messages were too fast for filmgoers to read but salient enough for the audience to register their meaning subconsciously. As proof, he presented data indicating that the messages had increased soda sales at the theater by 18 percent and popcorn sales by 58 percent.